Approaching 3.3 billion—half the world’s population.
“No technology has ever spread faster around the globe: the mobile phone took less than two decades to reach this degree of penetration.”
Actually I had one at work, about the size of a WW2 Walky-Talky, in 1983—which is almost three decades back.
I have a cell, of course. But I usually keep it in the car for breakdowns or other contacts of sudden need. I do not carry it about with me all the time.
THE TEXAS SCRIBBLER 
For me the cell phone is just another (and less used) function of that HTC thingy. But of course for some people it’s a full time job…